In general, the kinematics of opening of an aircraft door, for example a passenger door or a emergency door, is broken down into several steps which succeed one another, i.e. unlocking after releasing the lock by means of a safety latch, then disengagement of the door from its frame towards the inside of the cabin by appropriate guiding, and then pivoting of the door by actuators in association with a hinge around an axis of rotation. For the closure, these movements succeed one another according to inverse kinematics.
In emergency situations, it is required to be able to trigger the opening of the door in a minimum of operations in a minimum amount of time, whilst making the opening secure.
The regulations now require emergency doors to be able to be moved away without obstructing the emergency exits. In order to comply with this, emergency exit doors over the wing have been designed reusing the architectures of doors of the passenger type or cabin service type, and applying a reduction of scale. The stores of the passenger cabin type, which are pressurized in the cabin and provided with hinges, open automatically after activation of the inner handle and an articulation arm, with the door then being kept open along the fuselage.
According to the regulations, these overwing doors of the passenger type are certified as “dangerous”, because of their complexity, whereas the prior overwing doors (doors without a hinge known as a hatch can be thrown onto the wing as soon as the emergency opening takes place) were considered to be “non-dangerous” because their surface areas, larger than that of the passage hole in the fuselage, give rise to a very low probability of opening in flight. All the functions of the passenger and service doors must therefore be integrated in the emergency doors over wings, and therefore in a greatly reduced surface area, all the more so since the presence of a large window, identical to the windows of the fuselage, is now also required in the emergency doors.
In addition to all the functions of a so-called “dangerous” door to be integrated—double safety by means of a latch/lock during the locking/unlocking phases, secure opening/closure mechanisms, visual indicators and proximity sensors, assistance with the emergency opening and pressurization blocking mechanism if the door is not correctly closed—another parameter must be taken into account, i.e. the proximity of certain passengers to this overwing door, these passengers then being subjected to the thermal and acoustic problems which are associated with the presence of doors of this type. Consequently it is important to keep the maximum amount of space in the door structure in order to be able to install acoustic patches or thermal covers there.
An aircraft emergency door supported on lateral stops is known for example from the document of U.S. Pat. No. 5,031,863, which stops are in motion on rollers in guides, and are made secure by two latches situated in the threshold of the door.
The general kinematics of the door consist of a movement towards the inside then a movement of lifting of the top of the door in order to bypass the stops. The bottom of the door is guided in ramps, then the door opens automatically upwards, thrust by connecting rods with compression springs. The door is articulated by a hinge consisting of two arms in the form of a swan necks in the top part. The lifting of the door is generated by a cam connected to the top part of the handle. An inner handle is arranged above the window, and is actuated in a movement from the top downwards.
This door does not carry out all the functions of a door of the type which is “dangerous” according to the regulations, i.e. the double safety of the locking/unlocking phases and the pressurization blocking are not provided. In addition, this door can only be closed from the inside, and the locking mechanism is reduced to a hook at the bottom of the door.
Patent document U.S. Pat. No. 5,931,415 relates to a door of the automatic opening type, and proposes opening kinematics towards the inside coupled with descent in order to bypass the stops. The guiding is carried out by supports in ramps in order to impart the opening kinematics to the top of the door, whereas the bottom of the door follows a movement downwards then outwards. The door is retained in the open position thanks to a latch which automatically engages when opening takes place. In addition, the outer handle is connected to the shaft of the latch, whereas the inner handle is articulated relative to this assembly.
In addition, this door does not comprise a system which prevents pressurization if the door is not completely closed (“non-dangerous” door criterion according to the regulations). The ventilation panel of this mechanism is used as a pressure lock, in order to prevent the door from opening in the case of flight with low pressurization. In addition, this door does not have a safety system if one of the locks were to break. Finally, the kinematics of this door are complex, and the safety functions are not fulfilled.
In addition, the door according to patent document WO 2013128219 is articulated at the top by means of an arm and a set of rocker bars which are raised by a gas actuator. The virtual hinge articulation point is on the outside of the fuselage. The door opens after a low-amplitude movement towards the inside then upwards in order to bypass the stops.
The inside handle has a horizontal axis, is situated above the window, and operates from the top downwards. It makes it possible to open in emergency mode (toboggan armed) and in maintenance mode (toboggan disarmed). In addition to the particular kinematics with an instantaneous center of rotation situated on the outside of the door, this assembly does not fulfil the safety conditions in terms of double safety in locking and unlocking, and of a pressurization blocking mechanism (since the classification of this door is “non-dangerous” according to the regulations).